Telautograph apparatus



Sapt 10,

A. N. VAN NOSTRAN@ TELAUTOGRAPH APPARATUS Filed Sept. 29, 1928 2 Sheets-Sheet l v Xra,

Y.EA/TOR A d i A Troie/VE Y S 5% w A. VAN NOSTRANB TELAUIOGRAPH APPARATUS 2 Sheets-Sheet Filed Sepi. 29, 1928 Y l VEA/TOR l@ y 'C09 if," A Troie/v5 Y Cn Patented Sept. 1o, 1929.

lITI-:n STATES PATENT oFFIcE.

ARLEIGH N. 'VAN NOSTRAND, OF FLUSHING, NEW YORK, ASSIGNOR TO TELAUTO- GRAPH CORPORATION, OF NEW YORK, N. lY., A CORPORATION F VIRGINIA.

TELAUTOGRAPI-I APPARATUS.

Application led September 29, 1928. Serial No. 309,272.

The present invention relates to improvements in telautograph apparatus and particularly to improvements in receivers arranged to operate with variablestrength 5 direct current transmitters.

In such telautogr'aph apparatus the bueket coils which serve to operate the receiver pen are energized by currents sent out from the transmitter over the writing lines, these bucket coils being located in the lield produced by field magnets. The coils of the field magnets are energized by what may be termed a power circuit, because it carries a relatively heavy current as compared with the small currents of the writing lines. The power circuit may be energized by a single source of electricity, which may supply the entire telautograph system, or by local sources at each station. In order that the power circuit may be closed at the receiver from the transmitter as Soon as transmission begins and be opened as soon as transmission ends, it is common to provide a relay in one of the writing lines, this relay closing the power circuit containing the receiver field magnets s0 long as Writing current is flowing over the said writing line.

The vpaper shifter for the receiver has heretofore been included'in the power circuit so that the magnets of said shifter are energized to make one feed of the paper when thesaid writing line relay closes the said power circuit at the receiver, this paper shifter making a return lstroke under the infiuence of gravity, ready for another paper feedin action, when the said writing line relay 1s deenergized.

When the field magnets land the magnets of the paper shifter are energized from the power circuit and the closure of the. power circuit is accomplished by a relay in the writing line certain difliculties are encountered due to the discharge of the field magnetcoils through the paper shifter magnets when the power circuitis opened at the contacts of said relay, the discharge current from the eld magnets tending to ca'use an undesired paper feeding o eration of the paper shifter. To avoid' t is ithas been f-f) common to arranget-he paper shifter coils in multiple with the field magnet coils, and provide the line relay with twok sets of contacts, one set for short-circuiting a part of the field magnet winding when the relay is d eenergized, and the other set for closing simultaneously the power circuit containing the ield magnet coils and the paper shifter coils, the arrangement of the two sets of contacts being such that the line relay will close the short circuit for the field magnet coils before opening the power circuit and vice versa. This requires a delicate adjustment of the Contact devices and often leads to a resulting lack of reliability in operation requiring frequent inspection and considerable care in maintaining the proper adjustment of the contact points.

To avoid this disadvantage, the system at the receiver is sometimes modified so that the line relay is used to close only the branch of thepower circuit containing the paper shifter, and then the latter closes the branch containing the field magnet coils, for which purpose the paper shifter is provided with circuit making and breaking devices. In this construction the paper shifter also closes the pen lifter line at the receiver. As the paper shifter must make a relatively long stroke to feed the paper it becomes necessary to provide special circuit making and breaking mechanism which allows a long -movement to the operating mechanism with a short movement of the contact springs. Such an arrangement may lead to an undesirable braking action on the paper shift-l er, so that in case of any alteration of the adjustments of the apparatus, the strokebf the paper shifter is interfered with, with the result that the paper feed is not uniform.

It is the object of the present inventlon to provide a system and apparatus for the receiver circuits whereby the above disadvantages will be avoided. With this general object in View and some others which will be obvious to those skilled in the art from the description hereinafter given, the invention comprises a receiver system and apparat-us 4in which the line relay is provided with one set of contacts only, these contacts controlling a. branch o'f the power circuit i in which are includedin multi le the coils of thepaper shifter and the coils of a field control relay, this relay controlling another branch of the power circuit containing the eld magnet coils. This relay also controls two branches of the pen lifting line, closing one and opening the other and vice versa, one of these branches including the coils of the pen lifting magnet and thel other branch including the coils of a' signalling buzzer, the latter branch being closed when the field control relay is in its deenergized condition.' Furthermore, the complete system embodying the invention in its best form comprises means for protecting the field control relay contacts against the oscillatory discharge from the field magnet coils i due to-opening the circuit, and also comprises a high resistance winding on the field magnet 1n multiple with the usual energizing coils of said lield magnet, this high resistance winding being so wound that the oscillatory discharge through it will neutraliz'e the magnetizing effect of the discharge through the usual energizing coils.

The means for protecting the ield control relay contacts against the oscillatory discharge of the field magnet coils is most advantageously a shunt branch of the power circuit shunted around the said contacts and provided with a condenser to pass the oscillatory discharge, while blocking any direct current. v

The invention also comprises a relay construction articularly important in connection with t e receiver system hereinbefore pointed out.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which Fig. 1 is a diagrammatic view of so much of a telautograph receiver system las is necessary to explain the invention,

Fig. 2 is a front elevation of a field control relay embodying features forming part I of the invention,

Fig. 3 is an end elevation and Fig. 4 atop view of the said relay;

A Fig. 5 is a front elevation of a writing line relay embodying features forming part of themvention, and

Fig. 6 is a side elevation of the said line relay.

Referring to the drawings, and particu-r larly to Figs. 2 to 4, the field control relay comprises a U-shaped frame 4, of magnetic material one leg, 5, of the rame extending beyond the other. To the longnleg, 5, a plate spring, 7 of steel is clamped y a clamping bar, 8,held by two screws, 9, passing through the 'clamping bar and through the plate spring, 7, into the end of the leg, 5.

To the inner side of the plate spring an armature, 10, is secured in such a way as to allow acertain freedom of movement of the plate spring relativeto the armature and vice versa. This is accomplished by providing a short spacer block, 11, between the plate spring and the armature and securing the armature, the spacer block and the plate spring together in any suitable manner as, for example, by rivets passing through all the parts. In order to maintain a ood magnetic circuit the armature is made ong enough so that one end of it extends over the face of the short leg, 6, of the U-shaped frame, while the other end yof said armature reaches close tothe side of the long leg, 5, of the U-shaped frame, so that the air gaps willbe reduced as much as possible, the plate vspring itself assisting somewhat in reducing with the coacting contact points 14 and 15 y carried by the contact posts,th\is constituting two sets of front contact devices for a purpose hereinafter more fully explained; The plate spring, 7, also carries a back contact point, 18, which coacts 'with a contact` point, 19,J carried by the overhanging end, 20, of a back contact post, 21. The front` contact posts, 12 and 13, yand the back contact y post, 21, are constructed and mounted upon the U-frame as follows: Upon the short leg, 6, of the U-rame there is placed a plate member, 22, having an inturned flange, 22a. The front contact vposts 12 and 13 are mounted outside the vplate member, 22, and they together with the saidplate member are held securely to the short leg of the U-frame by screws, indicated at 23, passing through longitudinal slots in the front contact posts, thence through holes in the plate member, 22, and into threaded holes in the U-frame, suitable bushing washers, 24, of insulating material being provided vbetween the plate member, 22, and the respective contact posts, 12 and 13, so as to insulate the latter.

For the same purpose, the screws, 23, are prov1ded with insulated bushing washers 25, the bushings of which enter the slots in the contact posts. Outside the bushing washer each screw is rovided with a metal washer 26, and, outsi e this, with a spring locking washer 27, beneath the head of the screw. By loosening the two screws of a contact post, the said post may be adjusted longitudmally as desired and by then tightening fthe screws it may be clamped firmly in the ductor one end of each post is sloped outward and provided with a terminal screw and washer, 28, as indicated in the drawings. l The back contact post, 21, is secured to the lnturned flange 22a of the plate member by screws 29, suitable bushing washers 30 of insulating material, located on the screws between the contact post and the said flange, serving to insulate the back contact post from the inturned flange, 22. The screws also are provided with bushing washers 31, metallic washers 32, and spring locking washers 33. In the present construction the back contact post is provided at one end with a terminal screw and washer, as indicated at 34 and 35, in the drawings.

To the U-frame there is secured the usual magnet-core, 36, on which is fixed a magnet winding For. It will be observed that the lrelay hereinabove described has a divided magnetic circuit. That is, if it is assumed that the direction of the magnetic flux through the core is from the free end of the core toward its junction with the Uframe, the flux divides at said junction, part flowing back along one leg of the frame, and part along the other leg of the frame. "The plate spring 7, is made with such a setthat normally it slopes away from the end of the core and the short leg 6, of the U-frame, whereby the air gap between the armature l0 and the end of said short leg 6 is greater than between the armature and the end of the core 36. `Hence the reluctance of that branch of the magnetic circuit which includes the long leg 5 ofthe U-frame is less than the other branch of the magnetic circuit. As a result more of the magnetic flux will flow' and the armature reduces.

over said long leg 5 than through the short` leg 6 at the instant when the magnet is initially energized, the parts being so dimeiv sioned that the pull of the core 36 at this time will serve to draw the armature toward the core against the resiliency of that part of the plate spring between the point of attachment of the armature and the clamped end of the plate spring. As the armature approaches the core, the air gap between the end face of the short leg and the armature reduces, thereby decreasing the reluctance of that branch of the magnetic circuit. Simultaneously the air gap between the core As a result of these reductions in reluctance, the flux is materially increased and therefore there is a relatively strong pull on the armature to-y ward the latter end of its movement. The air gap between the end face of the short leg and the armature is greater angularly than the gap between the front contacts so that, at the moment these contacts close, the armature can still travel further towardthe core and short leg, Owing to the increasing pullon the armature it continues tof move toward the short leg after the front contacts `toward the core and short leg.

there is a relatively heavy pressure of the` have closed, this resulting in bringing into action the resiliency of that` part of the plate spring between the front contacts and the point of attachment of the armature. That is, the plate spring is slightly bowed inward Consequently front contacts against each other as well as a slight wiping or rubbing action of the coacting contacts, and, when the magnet winding is deenergized,a quick return of the plate spring to normal because of the strong resilient energy previously developed in the plate spring by bending it after the initial engage; ment of its front contacts. The slit in the end of the late spring, allows the tongues 7a, 7b, thus fibrmed to yield independently of each other, thus insuring a good contact between each set of front contacts. The set of the plate spring is such that in its normal position it will press its back contact point firmly against the back Contact point carried by the back contact post. In practice it is not always necessary to make the back contact post adjustable. The front contact posts, however, are made adjustable as hereinbcfore described, in order to adjust the spark gap bet-Ween the front contacts. Owing to the good electrical contact between the plate spring and the long end of the U-frame, the frame may be provided with a terminal post, :is indicated at 38 which is intended for the attachment of a conductor leading to ground or to a metallic return, as will 'be clear from the description hereinafter.

In the diagrammatic view, Fig. 1, the two writing lines of the receiver are indicated at Rr and Lr respectively the right writing line R1" extending from the-terminal post Rp to a junction J l0 with the negative return Xn of the power line, which is grounded at G7'. In the writing line is included the winding Cf 'of the right bucket coil. Also a resistance Or may be included in this line. The left writing line Lr extends from the terminal post Lp to a junction J ll with the negative return. In this left writing line at the receiver there is included the resistance OZ and the left bucket coil CZ, as usual. In ad dition, the'winding, Cs, of a left writing line relay is also included in the said left writing line. This relay controls one pair of con- 4 tact points which close and open a branch of the power circuit, which branch contains, in multiple, the winding, Ct, of a paper shifter magnet and the winding Fco of a field control relay, such for example as the,relay hereinbefore described. The-multiple branches of the power circuit which containthe said windings Ct and For are indicated llO at Xr'l and Xf/Q respectively, these being merged in the common branch Xra which includes the contacts controlled by the armature of the left line relay. The branch Xra ofthe power circuit is connected to the nega# tive return at the junction 512.

The parallel branches Xrl and X72 are connected to the positive power line, indicated at Xi?, and tothis there is connected Fml and Fm of the field magnets. Also onA each spool of the4 field magnet there is wound a comparatively small number of turns of resistance wire having a high resistance, vfor example 100 ohms, these resistance windings being indicated at @m1 and @m2, rerespectively. r1`hese windings are in multiple with the usual magnet windings Fmi, Fm, respectively, and are wound in the same direction. rlhese resistance windings serve to absorb to a large extent the i'ield magnet 'discharge which occurs where the circuit through Xr?) is broken.

'lhe field control relay has the Fixed end ot its armature grounded by a conductor X11?) connected to the negative return Xn at the junction (T13. An alternating current shunt indicated at Xrc and joined to the negative return at junction 515 serves to shunt the oscillatory discharge rom the iield' magnet windings around the contact points 14,16, of the relay, the shuntXrc including a condenser as indicated at 40.

The pen lifter line of the receiver, marked Pr, is divided into two branches, one of which contains the windings Pm of the pen lifter magnet and 'ends at one of the trent contacts of the field control relay, for example, Contact 15, while the other branch contains the winding Sm of the signal buzzer and ends at the back contact 19 of the ield control relay.

ln the diagrammatic illustration Fig. 1 no means is indicated for causing a trembling of the receiver bucket coils. Thismay be done in any of the old and well known ways as, for example, by employing a. slight pulsating current on each writing line or by providing the usual trembler buzzer in shunt with the ield magnet windings. As the means for accomplishing this action forms no part of the present invention it need not be described herein, vbut it is to be understood that some means for accomplishing suchv vibration or trembling of the receiver bucket coils is to be employed.

The operation of the receiver system is as follows: When the transmitter is put in operation to send variable strength direct currents over the two writing lines, the initial action o such a line current in the left writing line is to energize the left line relay winding Cs, whereupon the said relay attracts its armature and closes the contacts of the power branch XM, so that current mitter, the power charge from marrone will low from the positive power line Xp over the parallel branches Xrl and Xr to the junction -J 12 and thence' over the negative power line Xn. l.When the circuit is closed through the parallel branches Xf/l and Kw2 the windings Ct of the paper shifter and the windings For of the iield control relay are energized. The paper shifter operates in the usual way. rlhe held control relay when its windings are energized a+- tracts its armature and thereby closes its two sets or front contacts, while opening its set ci baclr contacts. One set of front contacts closes that branch of thel power circuit which includes the field magnet windings, thereby energizing them, the current flowing from the positive power lineA Xp over branch 25J/3, through the ield magnet windings Fmi, F7712., @fm/1, @m2, to the pair of.

front contacts, thence over the branch Xf/' to the junction at J1?) and backl through the negative powerline Xn.

Simultaneously with the closing of the field magnet branch by one pair ofiront contact points, the other pair of iront contact points closes, atthe receiver, that branch ot the pen lifter line which includes the windings Pm. ozt the pen lifter magnet. Vlhis puts the receiver in condition so that the pen litter may be controlled :trom the transmitter inthe usual manner. In this condition that branch oit the pen litter line which contains the signal buzzer windings Sm is open at the back contacts of the iield control relay. 5

W'hen the writing line relay is deenergized by cutting od the current at the transbranch XM. is opened by the return of the line relay armature to normal. Thereupon the field control relay is deenergized and its armature returns to normal. ri`his closes the back contacts and puts the branch containing the signal buzzer in condition to receive any signal currents which may be sent out from the transmitter. When the lield control relay closes its back contacts itopens the two pair of front contacts, thus opening the circuit through the field magnet windings and the circuit through pen lifter magnet windin s. At the opening of the circuit through tile field magnet windings, any oscillatory dis charge from said lield magnet windings will be shunted from the corresponding contacts of the field control relay through the branch XM. 1t is highly important to absorb the disthe windings of the paper shifter magnet and the field control relay at the time of breaking the power circuit through XM due to the opening of the contacts ot' the writing line relay. n

1n order to accomplish this result in an effective yet simple manner the windings Ct of the paper shifter magnet and thewind1 ings For of the field control relay are shunted by a common shunt branch X14 containing a condenser 41. In this way the discharge from the field control relay windings cannot affect the paper shifter but will be short circuited by the shunt branch. Also, the discharge from the paper shifter windings will be short circuited by said shunt branch and cannot affect the eld control relay. yMuch trouble in telautograph receivers has been due to the unreliability of the writing line relay. It will be remembered that in a telautograph apparatus of the variable direct current type the writing current for the left writ-ing is relatively weak when the transmitter stylus is close to the unison position, because at this time the maximum resistance of the left rheostat is included in the left writing line circuit. On the other hand when the minimum resistance of the rheostat is in the left Writing line curcuit, the writing current is greatly increased. rlhe range of variation of the writing line current causes diiliculties in operation of the left writing line relays hereinbefore known. The relay should be so sensitive that that it will operate immediately with the minimum current which exists on starting the apparatus and this requires that the moving parts be light and that friction be practically eliminated. On the other hand `the relatively heavy currents which occur during transmission produce a residual magnetism in the magnetic circuit of the relay, which tends to hold the relay closed even after the writing line current has ceased. This prevents the proper operation of the paper shifter which is controlled by the writing line relay. Therefore to insure the proper operation of the system, the present invention includes a special type of line relay. In this line relay the armature is arranged to drop away from the magnet core under the action of gravity, the initial start away from the "core being assisted by a spring action and the magnet being slightly assisted by spring action at the start in drawing up the armature.

A relay embodying these features is illustrated in Figs. 5 and 6. The frame of the relay is -U-shaped and made of soft iron, both legs 50 and 51 being of substantially equal length. The yoke 52 of the frame supports the magnet core 53 andthe coil 54. To the outer face of the leg 51 there is fixed a bearing plate 55 of non-magnetic material having a pair of posts 56, projecting downward. The armature 57 consists of a rectangle of soft iron of such length as to extend over the-end of the core 53; over the l end of the leg 51 and between the posts 56 of the bearing plate 55. That portion of the armature which is between the posts is provided on its lower face with a fine groove or notch extending entirely across the armature and arranged to receive a fine still wire rod 58 which passes through holes in the posts 56 and serves, in connection with the groove or notch, as a bearing for the armature at its outer end, while at the same time allowing a slight play of the armature on thc rod 58. The armature is provided on its upper side, which is next to the core, with a spacer or stop device of non-magnetic material, which serves to prevent an actual contact betweenv the armature and the end of the magnet core. In the present example this spacer or stop device indicated at 59 is the projecting end of a rivet hereinafter referred to.

' To the lower face of the armature there is secured a plate spring 60 which has one end projecting beyond the free end of the armature so as to extend over the end of the leg 50 and over the flanged end of a contact post 61. The plate spring Ais secured to the armature by two rivets, one of which is located over theiend of themagnet core and has its riveted end large enough to serve as the stop device or spacer 59 hereinbefore referred to. The inner end of the plate spring 60 is formed so as to extend away from the armature at an incline and to it there is soldered one end of a coiled flexible conductor 62 whose other end is secured to the bearing plate 55 thus insuring a'good electrical connection between the frame of the relay and the plate spring. To the upper surface of the plate spring at its outer, free end is secured a contact point, indicated at 63, arranged to coact with a contact point 64 carried by the outwardly flanged lower end of the contact post 61 which is supported by but insulated from the leg of the U-frame.

l/Vhile the contact post 6l may be connected to the leg 50 in any suitable way, it

is most advantageously attached by two l,

screws l65 threaded into the leg 50, the contact post being provided with holes larger than the screws, so as to receive bushing washers 66 of insulating material. Between the contact post and the leg are placed insulating washers 67. Between the bushing washers 66 and the head of the screws 65 are placed metal washers 68 and spring locking washers 69. The contact post 61 is not adjustable lengthwise but is accurately constructed to bring its contact point 64 to the correct position, and is made rigid enough to hold this position permanently.

To limit the movement downward of the, armature and its plate spring, a hook-like stop device 70 is provided, this being held to the leg 50 by a screw 71. In the best embodiment of the invention the inner face of the-hook portion of the sto device is pro-- vided with a contact point 2 which coacts with a contact point 73 fixed to the plate spring 60. By means of these two cont-acts is pulled up. These contacts act mechanically only and have no electrical function.

It willbe noted that the magnetic circuit through the leg includes'a relatively great air space between the free end of the armature 57 and the lower end of the leg 50. As a result, the reluctance over this branch of kthe magnetic circuit is so large that such branchmay be considered as not part of the magnetic circuit of the' relay, the leg 50 serving practically wholly as a mere support for the contact post 61 and stop device Therefore it may be assumed that the actual operative magnetic circuit of the relay is through the core, the leg 5l of the U-frame, the armature 57, the air-space be-l tween the core face and armature and the air-space between the end face of the leg 51 and the armature. rThe latter air-space is very small. The other air-space between the core and the armature is .such thatjthe contact pointl 63 carried by the plate spring 60 will contact with the contact point 64 on the contact post 61 before the stop 59 on the armature has encountered the end of the core. Hence, after the said contact points have closed, the armature is strongly attracted by the core and is pulled up until its stopl 59 rests against the core face. This final movement of the armature is possible because the plate spring, whose outer end is stopped by the engagement of the Contact points, flexes .into an arc-shape, thereby developing the resiliency of the plate spring.

Hence, when the magnetic circuit is de-energized the armature is -suddenly pulled down from the magnet core, not only by gravity but also by the reaction of the plate', This gives a quick break of the spring.

- electrlc circuit through the contact points.

The armature drops until the plate spring isstopped by the stop-device 70, in which condition the weightof the armature and plate sprmg is supported by the ulcrum pin or vrod 58 at one end and by the hook ofthe stop-device 70 near the other end. The weight carried by the latter is relatively slight.i yet of course causes a slight tension in the plate spring, so that in the open posi` tion ofthe relay, a partv of the weight of the armature and plate spring has developed a slight spring reactionin the plate spring, thereby in effect reducing the weight of the armature to be started upward when the magnetic circuit is energized. Hence, by properly proportioning the parts, the armature will respond quickly to the pull ofl the magnet core and is free to move upward untilthe contact point 63 on the plate spring touches'the Contact point 64 on the post, after which -the momentum of the armature carries it upward until its stop V59 strikes the face of the core, a part of the momentum being stored bybending the plate spring the combination, with bucket coils and writing lines, each writingl linefhaving a bucket coil therein, of a writing line relay provided with two contacts and having its windings included in one of'said writing lines, a power line arranged to be controlled by the said contacts of the writing line relay and having two parallel branches, a paper shifter mechanism having a magnet winding in-l eluded in'one of said vparallel branches, a :held control relay having its windings included in the other of said two parallel branches, a field magnet branch from the power line arranged t'o be controlled by the ield control relay, and a field magnet having itsv windings in said field magnet branch, the bucket coils of the writing lines being located in the field of the said field magnet. l

2. In a telautograph receiver apparatus, the combination, with bucket coils and writing lines, each writing line having a bucket coil therein, of a writing lline relay provided with two contacts and having its windingsincluded in one of said writin'g lines, a power line arranged to be controlled" a paper shifter mechanism having its winding included in one of said parallel branches, a field control relay having its windings included in the other of said two parallel branches and provided with a set of back contacts and two sets of front-contacts, a field magnet branch from the power line arranged to be controlled by one set of front contacts of the ield control relay, a field magnet having its windings in said eld magnet. branch, the bucket coils of the writing lines being located in the field of the said field magnet, a pen lifter line having two branches, one controlled by the set ofvback contacts of the field control relay and the other by the remainin set of front contacts of said relay, a signa buzzer hav- ,in its windings in that branch of the pen 1i ter line which is controlled by the said back contacts, and a pen lifter having its s comprising a U-shaped frame having two legs and a yoke portion, one of said legs being longer than the other, a magnet core secured to the yoke, a winding on said core, a pair of front contact posts secured to the short leg and insulated therefrom, each contact postcarrying a contact point, an armature arranged to extend over the end face of the shortleg and nearly to the side of the long leg, a plate spring having one end secured to the long leg, said plate spring having its other end free and slitted to form two tongues, each arranged to extend over the respective contact posts, and each carrying a contact point arranged to coact with the respective contact points of the front contactposts, said plate spring being provided with a set such that it tends to hold its contact points out of engagement with those of the front contact posts, a back contact post secured to the said short leg and provided with an end extending outside the plate spring and serving as a stop therefore, coacting back contact points located on the back contact post and on the plate spring respectively, means for securing the armature to the platev spring at a point intermediate their the back contact points together rmly when the relay is deenergized and being arranged to bring the two pairs of front contacts together before the armature has .completed its movement toward the core when the relay is energized, whereby the plate spring is bent as the armature completes said movement, and a non-magnetic stop device arranged to prevent actual contact 'of the core and armature.

4. In a telautograph apparatus a line rev lay comprising a U-shaped frame havin two legs and a yoke, a magnet core secure i to the yoke, a winding on said core, a. front contact post secured to and insulated from one leg of the frame, a contact point carried by said contact post, a bearing plate secured to the other leg of the frame and provided with posts at one end projecting beyond the leg of the frame, a pin extending through said posts, an armature having a groove near one end to receive said pin, said armature extending from the bearing plate to and 'over the end of the magnet core and terminating there, secured' to said armature and the front contact post, ried by the plate spring andv arranged to contact with the contact point on said post, and a stop devicev secured to that leg of the frame carrying thefrontcontact lpost and extending over extending below the plate ,spring to limit` the drop of the armature. v

'In testimony whereof, I have hereunto set my hand.

ARLEIGH N. VAN NOSTRAND.

ends, to allow bending of the -plate spring, said plate spring pressing va plate spring a contact point car, 

